Scuderia Toro Rosso Technical Director James Key, says the teams year away from using Renault engines has highlighted just how much the French manufacturer have improved.

The Faenza based squad switched to year old Scuderia Ferrari engines in 2016 at the last moment, following a row between parent company Red Bull Racing and then engine supplier Renault, over the lack of reliability and performance of their power units.

The disagreement was eventually put to bed and the Milton Keynes based squad opted to stay with the French manufacturer, albeit with engines rebranded under the TAG Heuer moniker.

The delay in sorting out their differences however, left Toro Rosso with little time to arrange a competitive deal of their own, and they turned to the Italian manufacturer, who had powered their machines prior to Renault.

But using 2015 specification engines without any possibility of updates, proved to be the wrong move, and whilst sister team Red Bull went from strength to strength, Toro Rosso’s performance dropped off dramatically by the end of the year.

For 2017, the Faenza based squad have made the decision to return to Renault power, and Key is looking forward to benefiting from the much improved progress Renault have clearly made on the performance front.

“I think they’ve turned a tricky situation that they had when we had them previously into a much more coherent, robust approach.

“They’ve definitely made very real progress. The power unit architecturally is different; it’s a much tighter installation as well now.

“The sort of feedback and information that we’re getting from them is positive and all well understood and we’re working very well from them.

“So I think they’ve definitely turned a corner from last year and that trend from what we can see at the moment is continuing I think.”

Having not fared too badly in the first half of the 2016 season, scoring some solid top ten finishes with Carlos Sainz Jr, the Faenza based squad know they can produce a strong chassis and will be competitive given an up-to-date engine that can be developed across the year.

“The good news is we will have the most competitive engine we’ll ever have had since the power units came in with the new Renault.

“They’re looking much stronger than they were when we last worked with them, and there’s no doubt that it’s an engine which will develop well as well, so we’re looking forward to that.”

The Dietrich Mateschitz owned team also have two drivers that now know the squad extremely well, and are still young and hungry to succeed in F1. It is a strong and talented line-up, both drivers with something to prove, which should spur them on to move the team forward in 2017.

“We’ve got a couple of drivers we know well – they know what to do, so there’s no driver training requirement for the coming year. It’s really up to us to make sure we put a chassis on the track which is as competitive as it can be.”